Development of a sustainable dispersive liquid-liquid microextraction based on novel hydrophobic and hydrophilic natural deep eutectic solvents for the analysis of multiclass pesticides in water

A novel green dispersive liquid-liquid microextraction (DLLME) technique based on two new natural deep eutectic solvents (NaDESs) was developed and applied to the extraction of multiclass pesticides in different environmental waters. A hydrophobic NaDES based on monoterpene thymol and myristyl alcohol was prepared in 2:1 M ratio and used as an extraction phase. Additionally, a ternary hydrophilic NaDES composed of alanine, kojic acid, and water in a 1:2:5 M ratio was prepared and applied as disperser solvent. The NaDESs were characterized by ATR-FTIR spectroscopy, NMR spectroscopy, and octanol-water partition coefficient (K-ow). The analyses were performed by GC-mu ECD. The effect of significant parameters influencing extraction efficiency was investigated through a one-at-a-times strategy. The optimized method was validated by matrix-matched calibration, repeatability, and recovery. The method was linear in the concentration ranges of 0.003-100 mu g L-1 for 14 pesticides and 0.013-50 mu g L-1 for two pesticides with the determination coefficients > 0.9712. The accuracy was assessed by recovery evaluation at the spike levels of 10 and 20 mu g/L, in the range of 63.7-104.5%, with RSD <= 9.7%. The method was applied to the analysis of five environmental water samples, and various pesticide residues were detected in river water and groundwater samples in the concentrations range of 0.36-1.10 mu g L-1. The greenness of the procedure was assessed using the Analytical Eco-Scale. This paper represents the first application of these novel natural deep eutectic solvents in DLLME and, also the first time, for the analysis of multiclass pesticides in water samples.